Heat treatment system

ABSTRACT

A monitoring system comprises an observation apparatus adapted to determine at least one characteristic of food to be heated by observing the food to be heated, and a mirror system to deflect the observation beam path of the observation apparatus between the observation apparatus and the food to be heated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage of, and claims priority to, Patent Cooperation Treaty Application No. PCT/EP2018/080954, filed on Nov. 12, 2018, which application claims priority to European Application No. EP 17201417.1, filed on Nov. 13, 2017, which applications are hereby incorporated herein by reference in their entireties.

FIELD

The present disclosure relates to a monitoring system and a heat treatment system comprising the same, in particular to a system for heating, baking, roasting or proofing of food to be heated like bread, dough, pizzas and roasts.

BACKGROUND

In recent years, heat treatment systems like ovens or proofing chambers for heating, baking, roasting or proofing food, comprising baking products like bread, dough, pastries and other products like pizzas and roasts, have been equipped more and more with sensors or other observation apparatuses, e.g. cameras, in order to observe and monitor the food during the heating, baking or proofing process. The observation apparatuses or sensors may be connected to a control unit that is able to analyze the sensor readouts and to detect a variety of characteristics of the food to be heated using artificial intelligence. Thus, it is possible to automatically detect the load quantity of the heat treatment system, to automatically identify the loaded food products, to automatically select the right heating/baking/proofing program and to assist users and to automatically and quickly adapt the program in accordance to the state of the food inside the heat treatment chamber.

In this context, it is desirable that the sensors or observation apparatuses are able to observe as many food pieces inside the heat treatment system as possible simultaneously during the process. However, geometrically, this is not always possible, because trays, racks, shelves and other components inside the heat treatment system, such as an oven or proofing chamber are in the way between the observation apparatuses and the loaded food pieces and the sensors and observation apparatuses do not have an unobstructed view onto the food to be heated. Moreover, the space inside the heat treatment system is often very limited due to energy reasons and lack of space. It would be possible to use more than one observation apparatus or sensor to overcome the above limitations; however, these sensors are often very costly. Thus, it is desirable to use as few observation apparatuses or sensors as possible and to have a high degree of freedom for arranging them inside the heat treatment system.

SUMMARY

Disclosed herein is a monitoring system and a heat treatment system comprising the same where the observation apparatus of the monitoring system has an unobstructed view onto the food pieces to be heated, a cost-efficient monitoring system and a heat treatment system comprising the same for food to be heated, and a monitoring system that is easily attachable to an existing conventional heat treatment system, such as an oven or proofing chamber for food to be heated.

According to an embodiment of a monitoring system, a monitoring system comprises an observation apparatus adapted to determine at least one characteristic of food to be heated by observing the food to be heated, and a mirror system to deflect the observation beam path of the observation apparatus between the observation apparatus and the food to be heated.

Thus, there is provided a mirror system arranged within the beam path between an observation apparatus and food to be heated such that beams, e.g. beams of light, are deflected at least once. The beam path of the observation apparatus may be defined as the totality of the light beams that are observed by the observation apparatus and that enter the observation apparatus. An observation beam path may be defined as the portion of the beam path of the observation apparatus that is transmitted from the food to be heated to the observation apparatus and that enters the observation apparatus. This has the advantage that the observation apparatus may be arranged in a position where it is most suitable and convenient and without being in the way or interfering while handling the food. Moreover, there is a higher degree of freedom for arranging the observation apparatus relative to the food to be heated, since there does not have to be a direct line of sight between the food to be heated and the observation apparatus.

Preferably, characteristics of food to be heated may be the temperature of the surface of food pieces to be heated, the humidity, the degree of browning level, or volume or shape of food pieces to be heated.

According to an embodiment, the mirror system further comprises a mirror being movable along an axis in order to have an even higher degree of freedom for arranging the observation apparatus and in order to observe a bigger quantity food to be heated or more food pieces to be heated. The food may be arranged on a conveyor belt. Thus, it is possible to continuously observe a food piece arranged on a moving conveyor belt. The food may pass through an industrial oven or proofing chamber.

According to another embodiment, the axis extends in a vertical direction in order to be able to observe food pieces to be heated that are arranged one on top of the other, or stacked in a vertical direction, e.g. in an oven with two or more trays.

According to a further embodiment, the monitoring system comprises at least two mirrors. This has the advantage that the observing apparatus may observe at least two pieces of food at the same time, or simultaneously, or one after the other, or sequentially in time, depending on the arrangement of the pieces of food relative to the at least two mirrors. The at least two mirrors may each be movable along an axis, and the respective axes may each be in a vertical direction.

According to a further embodiment, at least one of the mirrors is adapted to be rotatable around at least one rotation axis. This has the advantage that the field of view of the observation apparatus is modified or rotated together with the rotation of at least one of the mirrors. Thus, for example, it is possible to observe two or more pieces of food sequentially. Firstly, a first piece of food is observed, then the mirror is turned or rotated such that the mirror faces a second piece of food such that it is in the field of view of the observation apparatus, then again the mirror is turned or rotated and so on.

According to an embodiment, at least one of the mirrors may be adapted to be rotatable around at least one rotation axis and movable along an axis. It is preferred that the rotation around the rotation axis is conducted by a rotation apparatus, such as an electric motor or hydraulic system. The rotation apparatus may be controlled by a control unit that receives control information. The control information may be transferred from a control unit controlling a heat treatment system such as an oven or heat treatment chamber.

According to yet a further embodiment, at least one rotation axis of each of the at least one mirror crosses the center of gravity of the corresponding mirror. Thus, it is easier to rotate the at least one mirror around the axis since there is no turning moment.

According to yet another embodiment, at least a part of the mirror surface of at least one mirror has a convex form. Thus, it is possible that light from a broader solid angle are reflected by the at least one mirror and the angle of view and/or the field of view of the at least one mirror and subsequently the field of view of the observation apparatus is enlarged and therefore increased. Thus, the observation apparatus has a broader angle of view (wide angle view). In other words, more light beams arrive at the observation apparatus and enter the observation apparatus.

According to yet a further embodiment, at least a part of the mirror surface of at least one mirror has a uniaxial convex form or has a biaxial convex form. At least a part of the mirror surface of each of the mirrors may have a uniaxial convex form or may have a biaxial convex form. Thus, it is possible that light from an even broader solid angle are reflected by the at least one mirror and the angle of view and/or the field of view of the at least one mirror and subsequently the field of view of the observation apparatus is enlarged and therefore increased. Thus, the observation apparatus has an even broader angle of view (wide angle view). In other words, more light beams arrive at the observation apparatus and enter the observation apparatus.

There is further provided a heat treatment system, comprising a heat treatment chamber, trays having a food loading surface to be loaded with the food to be heated, the trays being stacked in a vertical direction inside the heat treatment chamber, and the monitoring system.

Thus, it is provided a heat treatment system, e.g. an oven or proofing chamber, comprising a heat treatment chamber, wherein it is possible to control the temperature and/or humidity of the air inside the heat treatment chamber, e.g. via a control unit and a heating device such as a heater blower. The heat treatment system may further comprise a rack or a rack system. The rack system may be inside the heat treatment chamber. Trays may be stacked within the rack system, the trays having a food loading surface. The food loading surface may be part of a recess of the trays. Inside the recess or on the food loading surface, food to be heated may be arranged. This may be pieces of food. The food pieces may be arranged in a uniform way. The trays may be stacked one on top of the other inside the heat treatment chamber. The heat treatment system may further comprise the monitoring system according to an embodiment. Thus, it is possible to observe several food pieces to be heated inside the heat treatment chamber at the same time, or sequentially in time.

According to an embodiment, the monitoring system is arranged at a loading side of the heat treatment chamber. Thus, it is possible to mount the mirror system in a comfortable and time-saving way on the heat treatment chamber. Moreover, maintenance and reparability are facilitated because the monitoring system is easily accessible.

According to another embodiment, the heat treatment system further comprises an illumination device configured to illuminate the food to be heated. Thus, more light is reflected from the food to be heated and therefore it may be observed more easily. The observation is more accurate because the accuracy of the observation apparatus is increased. More light beams reflected from the surface of the food pieces enter the observation apparatus.

According to another embodiment, the observation apparatus comprises a camera or an array of photodiodes. Thus, it is preferred that the observation apparatus comprises a camera or an array of photodiodes, since they are readily available and thus, very cost-efficient. The observation apparatus may comprise other sensors, e.g. acoustic, ultrasonic, electromagnetic or x-ray sensors. The observation apparatus may comprise more than one camera and/or array of photodiodes.

According to yet another embodiment, the monitoring system further comprises a heater to heat the mirrors in order to prevent fog on the mirror surface the. Thus, it is achieved that the mirrors and the mirror system are always and have optimal reflectivity. The mirror surface of the mirrors may further be coated with a repellent coating such that particles adhere and deposit less easily.

According to a further embodiment the monitoring system is attached to a window of the heat treatment chamber. Thus, existing conventional heat treatment chambers such as ovens or proofing chambers may be retrofitted with the monitoring system. The window may be at a front loading side of the heat treatment chamber and may be integrated into a door of the heat treatment chamber.

According to yet another embodiment, the monitoring system is arranged within the heat treatment chamber. Thus, it is possible to provide heat treatment systems having a monitoring system that have the same outer dimensions as existing conventional heat treatment systems.

According to yet another embodiment, the at least two mirrors have their highest reflectivity in the visible spectrum of light and/or in the infrared spectrum of light.

Those skilled in the art will recognize additional features and advantages upon reading the following detailed description and on viewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain principles of the invention. Other embodiments of the invention and intended advantages will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. The features of the various illustrated embodiments can be combined unless they exclude each other.

FIG. 1 shows a monitoring system according to an embodiment in a schematic cross-sectional side view.

FIG. 2 shows a monitoring system comprising a mirror being movable along an axis according to an embodiment in a schematic cross-sectional side view.

FIG. 3A shows a monitoring system comprising a mirror being movable along an axis according to another embodiment in a schematic cross-sectional side view.

FIG. 3B shows a monitoring system comprising a mirror being movable along an axis according to a further embodiment in a schematic cross-sectional side view.

FIG. 4A shows a monitoring system comprising two mirrors according to an embodiment in a schematic cross-sectional side view.

FIG. 4B shows the monitoring system of FIG. 4A in a schematic front view.

FIG. 5A shows a monitoring system comprising two mirrors each having a convex form according to an embodiment in a schematic cross-sectional side view.

FIG. 5B shows the monitoring system of FIG. 5A in a schematic front view.

FIG. 5C shows a monitoring system comprising mirrors wherein the mirror surface of the mirrors has a biaxial convex form according to an embodiment in a cross-sectional side view.

FIG. 5D shows the monitoring system of FIG. 5B in a schematic front view.

FIGS. 6A and 6B show a monitoring system comprising mirrors each being rotatable around an axis according to an embodiment in a cross-sectional side view.

FIG. 7 shows a heat treatment system comprising a monitoring system according to an embodiment in a cross-sectional side-view.

FIG. 8 shows a heat treatment system comprising a monitoring system and a heat treatment chamber wherein the mirror system is arranged at a loading side of the heat treatment chamber according to an embodiment in a cross-sectional side view.

FIG. 9A shows a heat treatment system comprising a heat treatment chamber and a monitoring system wherein the mirror system is attached to a window of the heat treatment chamber according to an embodiment in a perspective front view.

FIG. 9B shows a heat treatment system comprising a heat treatment chamber and a monitoring system wherein the mirror system is attached to a door of the heat treatment chamber according to another embodiment in a perspective front view.

FIG. 10 shows a heat treatment system comprising a heat treatment chamber and a monitoring system wherein the mirror system is arranged within the heat treatment chamber according to an embodiment in a cross-sectional front view.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustrations specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. For example, features illustrated or described for one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the present invention includes such modifications and variations. The examples are described using specific language which should not be construed as limiting the scope of the appending claims. The drawings are not scaled and are for illustrative purposes only. For clarity, the same elements have been designated by corresponding references in the different drawings if not stated otherwise.

The terms “having”, “containing”, “including”, “comprising” and the like are open-ended, and the terms indicate the presence of stated structures, elements or features but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

In the context of the present disclosure, “vertical” or “vertical direction” or “vertical orientation” refer to a direction z that is parallel to the vector or direction of the force of gravity. Accordingly, “lateral” or “lateral direction” or “lateral orientation” refer to a direction that is perpendicular to the vector or direction of the force of gravity. There may be defined a first lateral direction x and a second lateral direction y being perpendicular to direction x, and direction z being perpendicular to both direction x and direction y. The three directions may define a Cartesian coordinate system as shown in FIG. 1. According to the coordinate system, “down” or “downwards” point in the direction of the force of gravity. “Up” or “upwards” point in the opposite direction z. In a heat treatment chamber, lateral direction x may point from a back side of the heat treatment system towards a loading side of the heat treatment system, as can be seen, e.g. in FIG. 8.

FIG. 1 shows a monitoring system according to an embodiment in a schematic cross-sectional side view. The monitoring system 1 comprises an observation apparatus 11 adapted to determine at least one characteristic of food to be heated 2 by observing the food to be heated 2. The monitoring system 1 further comprises a mirror system 12 to deflect the observation beam path 11 of the observation apparatus 11 between the observation apparatus 11 and the food to be heated 2.

The observation apparatus 11 is adapted to observe and monitor the food to be heated 2. The observation apparatus 11 and the food to be heated 2 may be arranged such that, without the mirror system 12, the food to be heated 2 would not be in the field of view 113 of the observation apparatus and thus would not be visible to the observation apparatus 11. The mirror system 12 enables the observation apparatus 11 to observe the food to be heated 2 by deflecting a beam path 111 of the observation apparatus 11. Thus, at least one light beam 112 reflected from the surface 21 of the food to be heated 2 is deflected by the mirror system 12 such that it enters the observation apparatus 11 via the observation beam path 111.

Without the mirror system 12, no light reflected by the surface 21 of the food to be heated 2 would enter the observation apparatus 11 and the observation apparatus 11 would not be able to observe the food to be heated 2.

Food to be heated 2 may be dough pieces or pastries, such as bread, croissants, cookies, bread rolls, or pizzas or roasts. The food to be heated 2 may be arranged on at least one tray 34.

FIG. 2 shows a monitoring system 1 comprising a mirror 122 being movable along an axis 121 according to an embodiment in a schematic cross-sectional side view.

Thus, the mirror 122 is movable along the axis 121 being parallel to the lateral direction x between at least two positions 12 a and 12 b. At position 12 a, the mirror 122 deflects at least one light beam 112 a reflected from a first food piece to be heated 2 a. In position 12 b the mirror 122 deflects at least one light beam 112 b reflected from a second food piece to be heated 2 b. Thus, the light beams 112 a and 112 b enter the observation apparatus 11 via the respective observation beam paths 111 a and 111 b.

As a consequence, it is possible that the monitoring system 1 monitors at least two food pieces to be heated 2 a and 2 b. Firstly, the first food piece to be heated 2 a is monitored, the mirror 122 being in the first position 12 a, then the mirror 122 is moved along the axis 121 to the second position 12 b and the second food piece to be heated 2 b is monitored. Then, the mirror 122 may be moved along the axis 121 to a third position, or may be moved back to the first position 12 a.

Alternatively, it is possible to continuously monitor a food piece to be heated 2 a being transported, e.g. by a conveying band 35, along an axis 222. The axis 222 may be parallel to axis 121.

FIG. 3A shows a monitoring system 1 comprising a mirror 122 being movable along an axis 121′ according to another embodiment in a schematic cross-sectional side view, wherein the axis 121′ is parallel to the vertical direction z.

The mirror 122 is movable along the axis 121′ being parallel to the vertical direction z between at least two positions 12 a and 12 b. At position 12 a, the mirror 122 deflects the observation beam path 111 a between the first food piece to be heated 2 a and the observation apparatus 11. In position 12 b the mirror 122 deflects the observation beam paths 111 b between the second food piece to be heated 2 b and the observation apparatus 11.

As a consequence, it is possible that the monitoring system 1 monitors at least two food pieces to be heated 2 a and 2 b. Firstly, the first food piece to be heated 2 a is monitored, the mirror 122 being in the first position 12 a, then the mirror 122 is moved along the axis 121′ to the second position 12 b and the second food piece to be heated 2 b is monitored. Then, the mirror 122 may be moved along the axis 121′ to a third position for monitoring a third food piece to be heated, or may be moved back to the first position 12 a.

The movement between the positions 12 a and 12 b may be a continuous movement with a speed that is always greater than zero, or may be a stepwise movement. The mirror may be moved by a moving mechanism and/or a motor, such as an electric motor, or a hydraulic system.

Thus, it is possible to observe at least two food pieces 2 a, 2 b that are stacked in the vertical direction z, i.e., one on top of the other, on trays 34.

FIG. 3B shows a monitoring system 1 comprising a mirror 122 being movable along an axis 121′ according to another embodiment in a schematic cross-sectional side view, wherein the axis 121′ is parallel to vertical direction z.

A food piece to be heated 2 a is arranged on a tray 34, wherein the tray 34 is mounted on a conveying band 35.

The mirror 122 may be adapted to continuously deflect the observation beam path 111 a between the food piece to be heated 2 a and observation apparatus 11 while the food piece to be heated 2 is moving such that, at any moment in time, at least one light beam that is reflected from the food piece to be heated 2 travels to the observation apparatus 11 where it is sensed.

FIG. 4A shows a monitoring system 1 comprising two mirrors 122 a, 122 b according to an embodiment in a schematic cross-sectional side view and FIG. 4B shows the monitoring system of FIG. 4A in a schematic front view.

The mirror system 12 comprises two mirrors 122 a, 122 b. Food pieces to be heated 2 are arranged on a loading surface 341 of each of the trays 34. There may be at least two trays 34, preferably 5 or 10. The trays 34 are stacked in the vertical direction z, i.e. one on top of each other. The observation apparatus 11 may be arranged on a side next to the trays 34 facing upwards, or may be arranged facing downwards or facing in a lateral direction, e.g. lateral direction y. In another embodiment, the observation apparatus 11 is arranged above or below the trays 34. The mirrors 122 a, 122 b are arranged and adapted such that each of the mirrors 122 a, 122 b deflects at least one observation beam path 111 a, 111 b between a food piece to be heated 2 and the observation apparatus 11. In other words, at least one light beam 112 a, 112 b reflected from two different food pieces to be heated 2 on different trays 34 enters the observation apparatus 11 via the respective observation beam paths 111 a, 111 b. Thus the light beams 112 a, 112 b travel from the respective food pieces to be heated 2 to the observation apparatus 11 where they are sensed and observed.

Thus, it is possible to observe via the two mirrors 122 a, 122 b at least two, preferably several, food pieces to be heated 2 being arranged on a food loading surface 341 of at least two trays 34 in a stacking aspect ratio simultaneously. The stacking aspect ratio may be defined as the ratio between a length L and a height h, wherein the height h corresponds to the minimal vertical distance between two of the at least two trays 34 and wherein the length L corresponds to the maximal distance in the lateral direction x of two food pieces to be heated 2 that may be arranged on the same tray 34. The food loading surface 341 of the tray 34 may be part of an upward facing surface of the tray 34.

The stacking aspect ratio may be between 0.5 and 2, or between 2 and 7, or between 7 and 11.

The at least two mirrors 122 a, 122 b may have their highest reflectivity in the visible spectrum of light and/or in the infrared spectrum of light. In another embodiment, the at least two mirrors 122 a, 122 b may have a reflective coating that is semi-permeable for light in the visible range.

As can be seen from FIGS. 4A and 4B, it is possible to observe several food pieces to be heated 2 simultaneously with only one observation apparatus 11.

FIG. 5A shows a monitoring system 1 comprising mirrors 122 a, 122 b wherein the mirror surface 123 a, 123 b of each of the mirrors 123 a, 123 b has a uniaxial convex form according to an embodiment in a cross-sectional side view and FIG. 5B shows the monitoring system 1 of FIG. 5A in a schematic front view.

The mirrors 122 a, 122 b are arranged and adapted to deflect the observation beam paths 111 between the food pieces to be heated 2 on trays 34 a and 34 b, respectively, and the observation apparatus 11 such that at least one light beam travels from each food piece to be heated 2 on trays 34 a and 34 b to the observation apparatus 11 and is detected therein. The mirrors 122 a, 122 b have each a mirror surface 123 a, 123 b with a uniaxial convex form. There may be more than two mirrors 122 a, 122 b. Preferably, there may be as many mirrors as trays 34 with food to be heated. The mirrors may be arranged one on top of each other in the vertical direction z, as can be seen from FIG. 5B. In another embodiment, the mirrors may be arranged offset relative to each other in the lateral direction y and or in the lateral direction x.

In another embodiment, the mirror surfaces 123 a, 123 b may have a uniaxial convex form. The uniaxial convex form may be a uniaxial cylindrical form.

The radius of curvature of the mirror surface having a cylindrical form may be between 10 cm and 100 cm, or between 1 and 10 cm, or between 1 cm and 5 cm.

Thus it is possible to observe a larger area of the trays 34 and thus it is possible to observe more food pieces to be heated 2 since the mirrors 122 a, 122 b each having a mirror surface 123 a, 123 b that has at least a partially convex form may capture more incident light. Thus, light beams reflected from the surface 21 of food to be heated 2 from a broader solid angle are deflected by the at least two mirrors 123 a, 123 b and, subsequently, may enter the observation apparatus 11.

FIG. 5C shows a monitoring system 1 comprising mirrors 122 c to 122 f wherein the mirror surface 123 c to 123 f of the corresponding mirrors 122 c to 122 f has a biaxial convex form according to an embodiment in a cross-sectional side view and FIG. 5D shows the monitoring system 1 of FIG. 5B in a schematic front view.

The mirror surface 123 c to 123 f of each of the mirrors 122 c to 122 f has a biaxial convex form. In another embodiment the mirror surfaces 123 c to 123 f of each of the mirrors 122 c to 122 f may have a biaxial spherical form or a biaxial oval form. The radius of curvature in the first axis may be the same as the radius of curvature in the second axis, or may be different. The axes of the biaxial convex form may be perpendicular to each other. The mirror surface 123 c to 123 f of the mirrors 122 c to 122 f may be part of a surface of a sphere or of an oval. Each of the mirror surfaces 123 c to 123 f of the mirrors 122 c to 122 f may have the same size and shape or may have a different size and/or shape. Thus, it is possible that the mirrors 122 c to 122 f capture more incident light from a broader area around the mirrors 122 c to 122 f. In other words, the observation beam paths 11 from a larger amount of food pieces to be heated 2 may be deflected by the mirrors 122 c to 122 f such that light beams reflected from the larger amount of food pieces to be heated 2 travel from the food pieces to be heated 2 and enter the observation apparatus 11. Therefore, it is possible to observe more food pieces to be heated 2 simultaneously.

As can be seen from FIG. 5D, the mirrors 122 c to 122 f may be in a fixed position with regard to the field of view 113 of the observation apparatus 11 and may be arranged such that none of the mirrors 122 c to 122 f obstructs the observation beam path 111 between the observation apparatus 11 and the food pieces to be heated 2. In other words, one of the mirrors is arranged in the observation beam path 111 between any of the food pieces to be heated 2 and the observation apparatus 11.

FIGS. 6A and 6B show a monitoring system 1 comprising mirrors 122 g to 122 j each being rotatable around an axis 124 according to an embodiment in a cross-sectional side view.

The mirrors 122 g to 122 j are each rotatable around a rotation axis 124. The monitoring system 1 may comprise more or less mirrors, each being rotatable around a rotation axis. The rotation may be executed by an electric motor that is controlled by a control unit. Preferably, the rotation axis 124 is parallel to the second lateral direction y. For each tray 34 g to 34 j with food to be heated 2 arranged thereon, there is a corresponding mirror 122 g to 122 j.

In a deployed state, the mirrors 122 g to 122 j are each arranged such that they enable the observation apparatus 11 to observe food on the respective trays 34 g to 34 j. In other words, in the deployed state, each mirror 122 g to 122 j deflects the observation beam paths between at least a part of the food to be heated arranged on the corresponding tray 34 g to 34 j and the observation apparatus 11 such that at least a part of the food pieces to be heated 2 on the corresponding tray 34 g to 34 j are visible to the observation apparatus 11 and for each food piece to be heated 2 on tray 34 j there is a corresponding observation beam path 111 j between the food piece to be heated 2 and the observation apparatus 11.

In FIG. 6A the mirror 122 j is in the deployed state and the food pieces to be heated 2 arranged on the tray 34 j are observed by the observation apparatus 11. In FIG. 6B the mirror 122 g is in a deployed state and the food pieces to be heated 2 on tray 34 g are visible to the observation apparatus 11 and for each food piece to be heated 2 on tray 34 g there is a corresponding observation beam path 111 g between the food piece to be heated 2 and the observation apparatus 11.

In FIG. 6A, mirrors 122 g to 122 i are in a retracted state. In FIG. 6A, mirrors 122 g to 122 j are in the retracted state. In the retracted state the mirrors 122 g to 122 j do not obstruct and influence observation beam paths 111 g to 111 j of the respective other mirrors 122 g to 122 j. The retracted state may be defined as the default state.

Therefore, it is possible to construct a monitoring system 1 with mirrors 122 g to 122 j, wherein each mirror 122 g to 122 j is optimized such that, when being in the deployed state, a maximum of food pieces to be heated 2 arranged on the corresponding tray 34 g to 34 j are visible to the observation apparatus 11 and are therefore observable. The optimization may be conducted without considering the arrangement and dimensions of the other mirrors, since they may be in the retracted state. The retracted state of the mirrors may be optimized such that, when being in the retracted state, they cause a minimal obstruction of the field of view of the observation apparatus and hence a minimal obstruction of the observation beam paths between the food pieces to be heated 2 and the observation apparatus. Hence, the optimization and construction process is simplified. Thus, it is possible to construct a simpler and a more compact mirror system 12 and a more compact monitoring system 1. The complexity of the mirror system 12 may be reduced since only mirrors of one type and/or size have to be used in the mirror system 12. Thus, the costs of production and construction of the monitoring system 1 are reduced.

The mirrors 122 g to 122 j may have more than one rotation axis 124. The mirrors 122 g to 122 j may have a further rotation axis that is parallel to the vertical direction z. The rotation axes 124 of the mirrors 122 g to 122 j may cross the physical center of gravity of each of the respective mirrors 122 g to 122 j. In other words, the physical center of gravity of each mirror 122 g to 122 j lies on each of the respective rotation axes 124. Thus, the mirrors 122 g to 122 j are rotatable with only a small amount of force, since no turning moment has to be overcome when the mirrors 122 g to 122 j are rotated. If a motor is used for rotation of the mirrors 122 g to 122 j, a motor with a smaller power is sufficient. The costs of the monitoring system 1 are further reduced.

In another embodiment physical center of gravity of the mirrors 122 g to 122 j is different from the geometrical center of gravity of the mirrors 122 g to 122 j. A counterbalance may be attached to the mirrors 122 g to 122 j.

FIG. 7 shows a heat treatment system 3 comprising a monitoring system 1 according to an embodiment in a cross-sectional side-view.

The heat treatment system 3 comprises a heat treatment chamber 33, trays 34 having a food loading surface 341 to be loaded with the food to be heated 2, the trays being stacked in the vertical direction z inside the heat treatment chamber 33, and an observation apparatus 11.

The heat treatment system 3 may be an oven or proofing system, having a chamber 33 for heating food. In the inside of the chamber 33, the temperature and/or humidity may be controlled by a control unit and a heating and/or cooling element and/or a humidifier.

The monitoring system 1 may be fully accommodated within in the heating chamber 33, as can be seen from FIG. 7. In other words, the observation apparatus 11 and the mirror system 12 are in the inside of the heating chamber 33, or inside the space defined by the walls of the heating chamber 33.

The heat treatment system 3 may further comprise an illumination device 101 configured to illuminate the food to be heated 2. The illumination device 101 may emit light in the visible and/or in the infrared range of light. The illumination device 101 may comprise at least one illumination elements 1011 that emit light, e.g. bulbs, LEDs, halogen lamps or sodium lamps.

The observation apparatus 11 may comprise a camera or an array of photodiodes, or both. The camera and array of photodiodes may sense light in the visible range or in the infrared range, or in both.

FIG. 8 shows a heat treatment system 3 comprising a monitoring system 1 and a heat treatment chamber 33 wherein the mirror system 12 is arranged at a loading side 331 of the heat treatment chamber 33 according to an embodiment in a cross-sectional side view.

The heat treatment chamber 33 has six levels, each constituting a heat treatment chamber 33. In each heat treatment chamber 33, there is arranged a tray 34. On each tray, food pieces to be heated 2 are arranged. In the upper part of the heat treatment system 3 there is arranged a blower 6, e.g. a gas burner. The blower may be controlled by a control unit. An input/output device for operating the control unit may include a display 100, e.g. a touch display, and may include a keyboard and may be arranged at a front side 331 of the heat treatment system 3. The heat treatment system 3 may be an oven or a proofing chamber.

An air blower may be integrated into the blower 6. A fuel is burnt together with oxygen in the blower and the produced heating gases then flow from there into the radiators 8 that are provided at the top side and the bottom side of the heat treatment chambers 33. The radiators 8 constitute the heating elements. After passing through the radiators 8, the heating gases flow back to the blower 6.

Moreover, the heat treatment system 3 is equipped with a device for producing steam that is introduced into the heat treatment chambers 33.

The heat treatment system 3 may comprise a heater 102 to heat the mirrors system 1 and the mirrors comprised therein in order to prevent fog on the mirror surface.

On the front loading surface 331, the heat treatment chamber 33 may each comprise a door and/or a window 332 for loading and unloading the heat treatment system 1 with food to be heated 2.

As can be seen from FIG. 8, the monitoring system 1 comprising the observation apparatus 11 and the mirror system 12 is arranged at a loading side 331 of the heat treatment chambers 33. The loading side may be defined as a side of the heat treatment chamber 33 through which food to be heated 2 is loaded into the heat treatment chamber 33 and may be in the first lateral direction x viewed from a point within the heat treatment chambers 33. The observation beam paths between the observation apparatus 11 and the food to be heated 2 inside the heat treatment chambers 33 passes through the windows or doors 332.

FIGS. 9A and 9B show a heat treatment system 3 comprising a heat treatment chamber 33 and a monitoring system 1 wherein the mirror system is attached to a window 332 of the heat treatment chamber 33 according to another embodiment in a perspective front view;

The monitoring system 1 is arranged at a loading side 331 of the heat treatment chamber 33 of the heat treatment system 3 or the side, where the window 332 of the heat treatment chamber 33 is arranged.

The monitoring system 1 may be arranged between two glass windows of the window or door 332 at a loading side 331 of the heat treatment chamber 33.

In order to function properly, the observation beam paths 111 between the food pieces to be heated 2 inside the heat treatment chamber 33 and the observation apparatus 11 arranged at a loading side 331 must be able to pass through the windows or doors 332. Thus, the windows or doors 332 may have glass windows that permit a passage of electromagnetic waves and light.

As can be seen from FIGS. 9A and 9B, an existing conventional heat treatment system may 3 be easily retrofitted with a monitoring system 1.

FIG. 10 shows a heat treatment system 3 comprising a heat treatment chamber 33 and a monitoring system 1 wherein the monitoring system 1 is arranged within the heat treatment chamber 33 according to an embodiment in a cross-sectional front view;

The heat treatment system 3 comprises a heat treatment chamber 33 such as a baking oven. A trolley 16 comprising a rack system 161 and trays 34 with food to be loaded 2 thereon is provided inside the heat treatment chamber 33. The trolley 16 comprises wheels 162. The trolley 16 may be introduced into the heat treatment chamber 33 for loading the heat treatment system 1 via an opening of the heat treatment chamber 33. The opening of the heat treatment chamber may be closed by a door. The trolley 16 may be turned via a turning mechanism 163 inside the heat treatment chamber 33 during the heating process in order to ensure a uniform heating of the food to be heated 2.

The food to be heated 2 may be baking goods such as bread, pastries or dough. The food to be heated 2 is baked via hot air, which is produced in a heating device 13. In a closed circuit, the hot air is then guided through the heat treatment chamber 33 where it heats the food to be heated 2. The hot air is then guided back to the heating device 13. The hot air is transported by a ventilator 14. The heat treatment system 3 further comprises a steam generator 17 for producing steam.

As can be seen from FIG. 10, the monitoring system 1 is arranged within the heat treatment chamber 33 and is attached to a lateral side of the trolley 16. It may be connected to a control unit controlling the baking process including the heating device 13, the ventilator 14 and the steam generator 17, via a wireless connection or by a cable connection.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof. 

1.-15. (canceled)
 16. A monitoring system, comprising: an observation apparatus adapted to determine at least one characteristic of food to be heated by observing the food to be heated, and a mirror system to deflect the observation beam path of the observation apparatus between the observation apparatus and the food to be heated.
 17. The monitoring system according to claim 16, wherein the mirror system comprises a mirror being movable along an axis.
 18. The monitoring system according to claim 17, wherein the axis extends in a vertical direction (z).
 19. The monitoring system according to claim 16, wherein the mirror system comprises at least two mirrors.
 20. The monitoring system according to claim 16, wherein at least one of the mirrors is adapted to be rotatable around at least one rotation axis.
 21. The monitoring system according to claim 20, wherein the at least one rotation axis of each of the at least one mirror crosses the center of gravity of the corresponding mirror.
 22. The monitoring system according to claim 16, wherein at least a part of the mirror surface of at least one mirror has a convex form.
 23. The monitoring system according to claim 16, wherein at least a part of the mirror surface of at least one mirror has an uniaxial convex form or has a biaxial convex form.
 24. A heat treatment system, comprising: a heat treatment chamber, trays having a food loading surface to be loaded with the food to be heated, the trays being stacked in a vertical direction (z) inside the heat treatment chamber, and a monitoring system comprising: an observation apparatus adapted to determine at least one characteristic of food to be heated by observing the food to be heated, and a mirror system to deflect the observation beam path of the observation apparatus between the observation apparatus and the food to be heated.
 25. The heat treatment system according to claim 24, wherein the monitoring system is arranged at a loading side of the heat treatment chamber.
 26. The heat treatment system according to claim 24, further comprising an illumination device configured to illuminate the food to be heated.
 27. The heat treatment system according to claim 24, wherein the observation apparatus comprises a camera or an array of photodiodes.
 28. The heat treatment system according to claim 24, further comprising a heater to heat the mirrors in order to prevent fog on the mirror surface.
 29. The heat, treatment system according to claim 24, wherein the monitoring system is attached to a window of the heat treatment chamber.
 30. The heat treatment system according to claim 24, wherein the monitoring system is arranged within the heat treatment chamber. 